Cement mixture with significantly improved physicochemical and bacteriological properties that contains dopamelanin, precursors thereof, analogues thereof or derivatives thereof, as an additive

ABSTRACT

The present invention refers to a cement composition that contains dopamelanin, its precursors and/or its analogues as an additive in a maximum percentage of 30% of the cement. This additive substitutes water of the capillary nets. The mentioned cement mixture posses a water/cement relation of 0.2 to 0.4, optionally it can contain different sand and gravel proportions. This cement mixture generates strong chemical bonds, and increased scouring resistance, of at least 28% and a higher elastic resistance of the concrete, of at least 50%. Its cracking in early stages is very low or practically null. The present request also refers to the use of dopamelanin and/or its precursors and/or its analogues as an additive of the cement mixture that substitutes the capillary water proportion in the cementant mixture. Just as well the use of dopamelanin and/or its precursors and/or its analogues, in an aqueous solution, in less that 3%, as a concrete setting and curing agent, thus it significantly increases the ductility and scouring resistance of the cement mixture. This is, the novelty cement mixture improves the physicochemical and bacteriological properties of the usual concrete, being of special interest the notable increment related with compression resistance and ductility or relative displacements, suffering less damage in comparison with the mixture containing water. In a meaningful way, it also increases since early stages, the volumetric stability of the concrete, thus it intensifies its scouring resistance, which is inclusive transmitter to the metallic elements immersed in its interior, since certainly it significantly protects them from deterioration.

FIELD OF INVENTION

The present invention refers to the elaboration of a cement mixture withsignificantly better physical (mechanical), bacteriological andphysicochemical properties than conventional mixtures; due that thismortar contains dopamelanin and/or its precursors, and/or analogues,and/or derivatives, as an additive.

BACKGROUND

The conventional concrete is produced by mixing three essentialcomponents: cement, water and aggregates, to which eventually a fourthcomponent is added. This component is generically named as an additive,although the air is another component. Chemically, concrete is composedby the four most abundant substances on the crust of the earth(silicates, aluminates, iron and calcium components).

We can make clear that cement, one of the concrete components, was usedsince the beginning of the 800's and since then, the Portland cement hasbecome the most worldwide used cement.

Cement mixture can be hydraulic when setting and hardening, as theychemically react with water; or they can be aerial, when they set andharden in contact with air.

In both cement mixtures, the initial desirable characteristics of themixture or fresh concrete are: plasticity, moulding and easycompactibility. But this mortar will gradually turn rigid acquiring theaspect, behaviour and properties of a solid body forming the hardenedconcrete.

Consequently with this, the mechanical behavior and durability of thismaterial in the service it offers, depends on three basic aspects:

-   1. The characteristics, composition and properties of the hardened    cementing matrix: this implies the selection of an appropriate    cement mixture, the use of a convenient relation water/cement of 0.2    to 0.4 and the eventually use of a necessary additive, with all of    which it may result in a potentially safe quality.-   2. The quality aggregates, according to the functions that the    structure will perform, so that they do not represent the weak point    in the behaviour of concrete and its capacity to resist adequately    and for a long time to exposure and service conditions, to which it    is submitted.-   3. The cement matrix affinity with the aggregates and its capacity    to work together, depends on the physical and chemical    characteristics of the cement, the mineralogic and petrographic    composition of the rocks that conform the aggregate and the form,    maximum size of the particle and superficial texture of them.

Besides the physical characteristics, that contribute to the intrinsicquality of the concrete and that can be quantified, they are included:its mechanic resistance, elasticity, thermal properties and maximumparticle size; which allow establishing the cement mixture qualityaccording to the corresponding national and international standards(ASTM International). This is, the material utilized for the elaborationof the concrete affects the facility with which it can be poured andfinished, it also affects the time it needs to harden, the resistance itcan acquire and how well it covers the functions for which it wasprepared.

The way in which each one of the components of the cement mixturecontributes in its properties and particular characteristics arementioned straight away. The different kinds and classes of cementaffect the cohesion, workability, settling down and pouring at the timeof hardening, mechanic resistance acquisition, heat generation,resistance against attack of sulfate, dimensional stability (volumetricchanges) and the chemical stability (cement-aggregates reactions). Insome aspects, the influence of the cement is fundamental, but in othersit has a fewer importance because there are other factors that alsoinfluence and of which effects are more outstanding.

Water has two different applications as a concrete component: aninternal one when it is used in the mixture and other external whenconcrete is “cured” with it. Although in this applications the watercharacteristics have different effects on the concrete, it is desirableto employ water of the same quality in both cases. The qualityrequirements for the water used in the concrete mixture has no obligedrelation with the bacteriological aspect (as in case of drinkablewater), basically it refers to its physicochemical characteristics andits effects over the properties of the concrete and behaviour. Upon theundesirable effects that can show up because of the use of inadequatewater, they can appear in a short period of time (related with thehardening time and the initial resistances), in a medium period of time(with resistances after 28 or more days) and in a long term (can consistin attack for sulfate, the alkali-aggregate reaction and the scouring ofthe reinforcement steel). The quantity of water necessary for hardening,has a maximum proportion of 40% respect to the cement quantity. Thesupplementary or extra water can be in a proportion of almost a 30%more; it is not fixed and occupies certain volume in form of capillarypores in the hardened cementant mixture. The bigger the water excesspresence there will be more capillaries quantity in the cement paste.When the total quantity of capillaries correspond to a water/cementrelation (w/c)=0.7, the capillaries are so numerous that they are unitedbetween them forming a permeable net. In consequence, if you add 70 gwater to 100 g cement (w/c=0.7), the first 20 g are chemically fixed,the following 20 g are fixed by adsortion and the remaining 30 g stayfree in the capillary net.

In the conventional hydraulic concrete mixtures, the aggregates use torepresent approximately between 60% and 75% of the absolute volume ofall the components; that is why the remarkable influence that theaggregates characteristics and properties exert over the correspondingconcrete. There are diverse materials that with certain frequencyaccompany the aggregate, and whose presence is inconvenient, forexample: the undesirable fine materials (lime and clay), and organicmatter (humus and small fragments of roots, plants or wood), amongothers.

The additive, is a different material to the water, the hydraulic cementaggregates and the reinforcement fibers, and it is added to the mortarimmediately before or during the mixing (American Concrete Institute orACI 116(26)). This is, the concrete additives are used for thefundamental purpose to modify, in a convenient way, the behaviour of theconcrete in its fresh state, and/or induce or improve determineddesirable properties in the hardened concrete. This will represent alower cost because of energy saving, for example increasing the defensecharacteristics against freezing and thawing, the delay or accelerationof the hardening time and a very high resistance is obtained, to mentionsome.

Some of the cement mixture components can be organic, containing Nand/or fat acids in their structures, can be thermoplastic that ingeneral increase the tension force and its flexibility. As shown by thepatents or patent requests: MX/A/2004/010631, WO2006/116387 A2,MX230744, MX221807, MX167038, PA/A/2006/005553, JP2004231497,JP2001213649, KR20010027978, ES2,030,845, JP11107459, RU2275342. Somecement mixtures hold elements to prevent scouring (MX154260, MX187569,PA/a/2006/005091, JP2004231497). Also, many other cement mixtures havebeen described (GB 2,398,296, JP2004224647, USRE37,655,MX/PA/A/2002/012612, U.S. Pat. No. 6,755,907, DE4324190, JP2003107025,JP4292447, JP9296033, MX 191331, PA/a/1999/008311, MX160941,PA/a/1999/02182, PA/a/1996/05755, MX241331, PA/a/1998/09713, MX253295,MX/A/2008/003801, WO1995/13995, WO01/14277).

Additives can be nanoparticles (US2008/0242769A1), can be antimicrobials(US 2008/0242769 A1), they can be granular, polymeric and/orwater-soluble; all of which are added with the purpose of preventingcontaminations, increasing flexibility, acoustic insulation andadhesivity, among others (MX 238915, JP8059325, ES2135634, CH679665,DE3436215, DE3143071, U.S. Pat. No. 3,042,608, U.S. Pat. No. 6,902,002).Other additives are made out of worn out materials (KR20030088716,ES2152197, DE19728164).

Particularly, in this patent request, dopamelanin and/or its precursorsand/or its analogues and/or derivatives, is/are used as an additive,considering and taking advantage due to peculiar characteristics of thiscomponent.

Lets remember the extraordinary melanin and melanocite propertiesrelated to water (melanin, in presence of light, dissociates water);these properties have been glimpsed relatively short time ago; thus thepublications that called the attention related to the theme initiatedaround 1996. Since 1997 it has been proposed (Solis Herrera, 1997), toutilize the unusual capacities of melanin molecule for diverseindustrial processes, such as reusable energy generation, for medicinalpurposes, and this document proposes the melanin utilization to improvethe concrete qualities in the curing processes, improving its physicalresistance qualities, flexibility without diminishing drastically itsmechanic capacities (ductility) and scouring resistance, that cause lossin steel-concrete adherence and nominal diameter in the reinforcementsteel, which in many cases is the cause of collapses, in more or lessgrade and in direct or indirect form.

Melanin posses chemical, biochemical and electronic properties that havenot been clarified, detected, understood, or predicted in its whole; butone of them is that melanin generates molecular oxygen and hydrogenderivated from the water photolysis. This is based on the followingreaction:2H₂O

2H₂+O₂+4e ⁻

For this cause, to more the melanin, the concrete will dispose of amajor quantity of molecular oxygen and hydrogen, as well as energy andhigh energy electrons to carry out diverse chemical reaction thatregularly occurred in all the components, from which concrete is not theexception.

OBJECTIVE OF THE INVENTION

Considering that concrete is the second substance (after water) mostlyused by the man, the objective of the present invention is to present anew concrete mixture with significantly increased resistance,flexibility (ductility), compactness and scouring resistance properties.

DETAILED DESCRIPTION OF THE INVENTION

Based on the fabrication experience of concrete mixtures withdopamelanin and/or its precursors and/or its analogues and/or itsderivatives, the cement mixture qualities related with thecharacteristics and properties of the additive utilized in thisinvention, have been analyzed.

The internal structure of the new cement mixture has an increaseddensity (due to a higher molecular attraction) and a higher homogeneity,which raises its flexibility and avoids fault areas during the hardeningprocess. These characteristics are related with the capacity of additiveto diminish the air bubbles immersed in the mixture and the molecularrepulsions. Moreover, its combination capacity (as bonding) facilitatesmolecular approximation. In other side, the consistence of cementmixture is softer and significantly more plastic, easy to handle andtherefore much more easy to work with.

Other characteristics, that depend on the internal structure of cementmixture, are a higher resistance, flexibility (ductility) and scouringresistance, due to molecule size of the melanin (estimated in millionsof Daltons) and presence of charges; for this cause the additive can bediluted in water at different concentrations, but inclusive inconcentrations under 3% of the volumetric weight (weight/volume). Thesecharacteristics, present in the new mixture, are important in theconstruction field. For example, in the seismic response demand for thedifferent service states to which structures are submitted, allowing theutilization of more slender (plastic) structural elements, with fewerreinforcement steel quantities (example, steel bars), which leads to acosts decrease and the possibility to construct bigger clear spaces withless structural elements (as columns).

The new cement mixture holds scouring resistance properties due to theantirust quality of the additive. Therefore, the presence of theadditive inhibits microorganisms growth, because of the presence ofmolecular oxygen resulting from the activity of dopamelanin over thewater molecules (anaerobic microorganisms are specially inhibited), sothat the mixture can be used in humid zones. Also, the attack of diversexenobiotic substances that deposit into the structure (and come fromknown or unknown sources, from dangerous or harmful substances), areadsorbed or absorbed and later gradually liberated in a modified way, ina high or low grade, depending on each substance, its structure/activityrelation or the presence of sulphidryls, among others.

The major stability of the cement mixture presented by this invention isalso due to the intrinsic property of the dopamelanin buffer; avoidingthe temperature or the acid/alkaline media actions, which prevents thedeterioration of the mixture and eventually avoids the collapsestructure in its whole. In the other hand, the mixture that possessactivity of dopamelanin, results in a more complete one because it iscapable to produce a major availability of high energy electrons andmolecular oxygen and hydrogen, combined with its capacity to absorb abig and diverse compounds quantity and diversity. This creates astructure with a major efficiency, generated by the new mixture, capableto promptly respond to the different environmental, extraordinary,circumstantial or everyday solicitations (affronts, abrupt changes,attacks), resulting from the forces or the changes in themselves(moments), that conduce to deterioration of the structure related withaging. This means that the structure formed from a mixture that has ahigher dopamelanin quantity will present a higher tolerance capacity tobiochemical and physical affront, comparing against a concrete with afewer additive quantity.

Other characteristics, different from the conventional concrete, havebeen observed in the new one. For example, related to appearancemixture, it has a darker color, with a pleasant to the view aspect. Itis notorious that concretes made with the additive have no odor, incontrast with conventional ones, that can be explained because thedopamelanin forms covalent links with the thiols, that are one of themolecules that most commonly relate with aromatic compounds. On theother hand, considering the usual concrete heat-emitting reaction,perceptible when they are applied, in the concrete added with melaninthe temperature changes are less pronounced, this means that thereactions are more stable because they loose less energy in form ofheat. Since dopamelanin allows that a larger energy quantity can be usedin the formation of different types of chemical links; this is why it isa “cooler” concrete when it is touched. Its higher workability allowsfiner and more precise finishes; with a major adaptability to thecentering or mold used for its pouring, since it is easier to copy theirform with less added process, like vibration. The phenomenon known as“draining”, (paste and rocky aggregates segregation), decreasesdrastically when the additive is used, du to that the vibrationprocesses are present in a less quantity and frequency than in aconventional concrete. The mixture exhibits a higher adhesivity, whichin case of the finish, allows to apply a more uniform, esthetic andpleasant to the view and touch layer, with much less effort or work.

One of the applications that this cement mixture possess, is linked withbuildings related with gamma ray emission (for example nuclear centralstations), the mixture is capable to absorb radiations due to thedopamelanin presence. For this reason, apart from having walls 50% lessthick in comparison with walls constructed with the conventionalmixture, isolation from these lethal radiations is much more effective.

The structure/activity relation of the concrete/additive interfaceallows to utilize it as a self-leveling concrete, which in extensionscases such as pavements, it represents an important saving in theworkmanship required for a better finish, which in the case of melaninwould be significantly less.

Related to sun exposure, the structures constructed with the new cementmixture, when hardening they will have a more uniform temperature,despite the differences in the solar radiations they received related toareas exposed to a higher or lower sunlight quantity. The chemicalreaction has fewer temperature differences within the concrete mixture,generating a much more adequate structure for the purpose to which it iscalculated. The chemical stability conferred to concrete by dopamelanin,also offers advantages related to the hardening process because thehardening temperature is more stable, in fact the advantages are presentsince the additive is added, and also when it is aggregated during thehardening (external humectation), with the purpose of reducing moregradually the humidity range; which results in a hardened concrete withbetter properties.

Summarizing, dopamelanin, its precursors, analogues or derivatives areused in cement mixtures as an additive that gives remarkablecharacteristics such as:

-   -   a) Antirust:        -   When applied to concrete prevents oxidizing latent zones in            the reinforcement steel, which avoid subsequent faults of            the elements because of rusting or inclemency actions.        -   With this the steel preserves its geometric properties            without being affected by rusting caused by the oxygen-steel            with its different alloys reaction.        -   It can be used in places where exposure to alkali and            environmental relative humidity, is considered high.    -   b) Its increases mechanical properties:        -   When incorporated to the cement-sand and cement-gravel-sand            mixtures, it generates a tempered exothermic reaction, with            this the concrete contraction diminishes remarkably and the            cracking in early stages is very small or practically null.        -   Generates high attraction chemical bonds and with this,            increases its compression capacity, so its vacuum relation            is low, with this a more dense element is obtained. This            means: its density and volumetric stability is significantly            higher, which makes it more predictable.        -   At the same time it intensifies its mechanical properties in            the presence of lateral demands, increasing its elastic            range and as consequence there is less damage in the            elements (ductility).        -   Diminishes the transversal sections of the elements and the            amounts of steel required for certain displacement demands.        -   Aggregating a major additive quantity to the mixture in            latent zones of the plastic hinges, increases its rotation            and joint generation capacity for the energy dissipation            during an earthquake.    -   c) Improves finish of the elements.        -   Dopamelanin additive, its precursors, analogues or            derivatives, in an aqueous solution, when incorporated to            the cement-sand and cement-gravel-sand mixture, it            significantly diminishes vacuums formation, usually            generated by the mixture with water. The resulting texture            is sight pleasant.        -   Requires less vibration at the time of cast of the elements            diminishing a possible segregation in the mixture and as a            consequence, a drainage in the concrete.

One of the advantages offered by the additive in the cement mixture isthat it allows the construction of:

-   -   a) Masonry junctions.    -   b) Profound foundations.    -   c) Elements exposed to high relative humidity or that are        submerged in aqueous media.    -   d) Shear walls in masonry buildings.    -   e) Concrete elements in buildings located in high displacement        demand areas (seismic zones).    -   f) Elements that require capricious forms and fine finishing.

When it is fresh, the new cement mixture reaches a major density, ismore homogeneous, stable, flexible, it has a higher castability, and abetter workability. These characteristics appear much more quickly thanin the conventional mixture. This means, its hardening is accelerated ina notorious way, thanks to higher energy availability, carried by thehydrogen that results from the water dissociation caused by dopamelanin.This allows that the chemical reactions that conform the whole (of theconcrete), take place in a more efficient way, given the higher hydrogenavailability and therefore its valuable energy charges. Remember thathydrogen is the energy carrier mostly used by Nature in the universe.These characteristics produce a more firm hardened cement mixture, witha higher scouring resistance, a bigger microorganism growing inhibition,a more stable temperature, capability to absorb more longelectromagnetic radiation wavelengths, (including gamma rays), it has adarker color, is odorless and pleasant to the touch and sight. Thementioned above is related with a different water molecule in presenceof dopamelanin, since for example, evaporation is drastically reduced.

The present invention claims a cement composition that comprisesdopamelanin, and/or its precursors and/or its analogues as an additive,in a maximum percentage of the 30% of the concrete, this additivesubstitutes water of the capillary nets said cement mixture possess awater/cement relation of 0.2 to 0.4, but not limited to this proportion,and optionally it can contain gravel and sand in different proportions,said cement mixture generates strong chemical bonds (due to the higherenergy availability carried by hydrogen), and an increased scouringresistance, at least 28% and a higher elastic resistance of at least50%, with a low or practically null cracking within the early stages.

The present request also claims the use of dopamelanin and/or itsprecursors and/or its analogues, as additive of the cement mixture thatsubstitutes the capillary water proportion in the cement mixture. Oreither the use of dopamelanin and/or its precursors and/or itsanalogues, in an aqueous solution, in a percentage of minus 3% (but notlimited to), as an agent for setting (hardening) and curing the cement,which significantly improves the ductility, resistance and scouringresistance of the cement mixture. Summarizing dopamelanin significantlyimproves the physicochemical and bacteriological properties of theconcrete.

EXAMPLES

A cement mixture was made using dopamelanin as an additive, thisadditive is chemically synthesized with a black opaque color and atotally liquid consistency.

It was synthesized within the major quality and similarity standards tothe organic compound. The additive was applied substituting the portionof the water in the

MAXI- MUM RESIS- SPECIMEN AGE BASE RISE LENGTH APPLIED TANCE TYPE (days)(cm) (cm) (cm2) CHARGE (kg/cm2) Cement 30 days 19.86 3.83  76.156 23.048322.46 with dopamelanin Cement 30 days 19.80 3.675 72.765 18.315 251.25without dopamelaninmixture, without disturbing water/cement relation, that was previouslycalculated for the resistance required by the mixture

Compression tests were realized to mortar tiles and bending essay teststo cement mixtures with dopamelanin and specimens without dopamelanin.The compression tests applied to cement tiles were realized in anaverage of three specimen proof for the cement with dopamelanin and inan average of two specimen proof for the cement without dopamelanin.

The results show that the cement with the cement without dopamelaninpresents a maximum resistance of maximum resistance of 326.14 kg/cm2, onthe other hand the cement without dopamelanin presents a maximumresistance of 274.69 kg/cm2; the cement with dopamelanin supports atleast 25% more of maximum applied load respect to the cement withoutdopamelanin and the resistance increases at least 28% respect to thecement without dopamelanin.

Bending essay tests were made to cement with dopamelanin and cementwithout dopamelanin samples, the following chart shows an average of thefour tested samples for cement with dopamelanin and three tested samplesfor cement without dopamelanin.

MAXIMUM SPECIMEN AGE LENGHT AREA APPLIED TYPE (days) (cm) (cm2) CHARGECement 30 days 3.90 19.87 20.00 163.69 0.495 with dopamelanin Cement 30days 3.86 19.80 19.73 150.92 0.486 without dopamelanin

The cement with dopamelanin supports a maximum applied load of 163.69kgf, to say, it supported at least 30% more of the maximum applied loadrespect to the cement without dopamelanin. Besides, the cracking inearly stages is very low or practically null, comparing it with theconventional cement.

Since the process for mixtures implementation, it is easy to perceivethe difference between both, since the mixture with dopamelanin tends tostabilize faster, in comparison with the mixture with water, becausethis last one requires a 20% more cement to reach the stability ofdopamelanin mixture. This increase is the setting velocity, is acharacteristic that has relevant practical applications, for examplewhen applying in high relative humidity zones.

What is claimed is:
 1. A cement composition comprising: dopamelaninand/or precursors of dopamelanin and/or analogues of dopamelanin and/orderivatives of dopamelanin, as an additive in a maximum percentage of30% of the cement, the additive substitutes the water of capillary nets;said cement composition possesses a water-cement relation of 0.2 to 0.4,and optionally includes different gravel and sand proportions; saidcement composition generates strong chemical bonds, a higher scouringresistance of at least 28% and a higher elastic resistance of concreteof at least 50%, thereby having a significantly lower cracking in earlystages in comparison with conventional concrete.
 2. An additive in acement mixture comprising: dopamelanin and/or precursors of dopamelaninand/or analogues of dopamelanin and/or derivatives of dopamelanin, theadditive substitutes a capillary water proportion in the cement mixture.3. An agent for setting and curing concrete comprising: dopamelaninand/or precursors of dopamelanin and/or analogues of dopamelanin and/orderivatives of dopamelanin in an aqueous solution, in a concentration ofbelow 3%, and which increases physicochemical and bacteriologicalproperties of the concrete.